1. Field of the Invention
This invention relates to a dental fastening device. More specifically, this invention relates to a dental fastening device for fastening a wax substructure or wax coping of a subsequently fabricated dental bridge adjacent to a first and second dental die during the fabrication and shaping of the substructure where the substructure includes a pontic portion disposed between a first and second abutment portion such that the fastening device inhibits relative movement between the pontic and abutment portions during hardening and shrinkage of the substructure.
2. Information Disclosure Statement
In the fabrication of a dental bridge several steps are involved. These steps include initially taking an impression of the patient's mandible and maxillary until the subsequent fitting of the dental bridge.
More specifically, a doctor involved in the preparation of a dental bridge will take a wax impression which includes an impression of the abutment teeth and the pontic portion that is to be bridged. The impression will then be sent to a dental laboratory for fabrication of the bridge.
In the case of a patient requiring a standard bridge extending from a first to a second abutment tooth, the pontic portion is that portion disposed between the first and second abutment teeth. This type of bridge is provided primarily as a prosthetic device in order to serve the purpose of the tooth that previously occupied the position of the pontic portion of the dental bridge.
As will be well known to those skilled in the art, several variations of the standard bridge have been fabricated in dental laboratories including cantilever bridges in which a pontic portion is bridged to an adjacent abutment tooth. Furthermore, more than two suitably prepared abutment teeth may be spanned by a plurality of pontic portions according to the particular need of the patient being treated.
Particularly with regard to the present invention, a standard bridge will be exemplified in which a first and second abutment tooth are prepared for the subsequent fitting thereto of a bridge with a pontic portion disposed between abutment portions of the bridge.
When the doctor has taken an impression of the patient's mandible and maxillary including an impression of the first and second abutment teeth and the intervening pontic portion, these impressions will be sent to a dental laboratory for fabrication of the bridge.
The dental laboratory will use the impression of the first and second abutment teeth and intervening pontic portion to provide a replica of that portion of the patient's jaw in "stone". Usually, this "stone" replica or cast is of plaster of paris or other hardenable material. When the cast replica has been formed, the first and second abutment tooth replicas and the pontic portion will be cut from the cast and the individual replicas of the teeth and pontic portion known in the art as dies are individually mounted and are correctly aligned on the cast. Such alignment is accomplished with the aid of a dental articulator in which a replica of the corresponding opposite jaw of the patient is used to insure correct alignment and positioning of the first and second abutment teeth dies and the intervening pontic portion die.
After the removal of any undesirable undercut portions on the dies, the dental technician will hand wax the first and second abutment dies and the intervening pontic die such that the pontic portion of the substructure extends between the first and second abutment portions of the substructure. One way of hand waxing is accomplished by dipping the die in a preheated wax bath such that an even coating of wax known in the art as a coping adheres to the die.
In the prior art, problems have existed at this stage of fabrication because as the wax hardens and shrinks over the surface of the abutment dies, there exists a strong tendency for the connecting portions or interproximal areas between the abutment portions and pontic portion respectively to shrink or move relative to each other. Such relative movement results in a badly fitting dental bridge. The wax substructure or coping is used in the fabrication of a subsequently formed metal bridge by the well known lost wax or investment casting process and because of the resultant metal bridge is a replica of the wax coping, any imperfections in the coping will be reproduced in the metal bridge. Therefore, the resultant metal casting will be a replica of the distorted wax substructure.
The present invention seeks to overcome the problem of relative movement between the abutment portions of the wax substructure and the pontic portion thereof by providing tie downs which extend around the abutment portions of the wax substructure to firmly fasten the abutment portions in place during hardening and shrinkage thereof.
Therefore it is a primary objective of the present invention to provide a dental fastening device which overcomes the aforementioned inadequacies of the prior art devices and to provide a method of fastening the abutment portions of a wax substructure during hardening and shrinkage of the substructure to provide a subsequently fabricated dental bridge that will be an accurate fit.
Another object of the present invention is the provision of a dental fastening device in which movement between connecting portions or interproximal areas between the abutment portions and pontic portions respectively is inhibited.
Another object of the present invention is the provision of a dental fastening device in which the elongate tie down members are of elastomeric material such that the abutment portions of the wax substructure will be urged into mating engagement with the corresponding abutment dies.
Another object of the present invention is the provision of a dental fastening device in which each of the tie down members define at least one longitudinal slit disposed in the vicinity of the occlusal surface of the abutment portion of the wax substructure such that relative rotation between the wax substructure of the abutment portion and the corresponding dental die is inhibited.
The foregoing has outlined the pertinent objects of the present invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Particularly with regard to the use of the invention disclosed herein, this should not be construed as limited to the provision of dental fastening devices for the subsequent fabrication of standard dental bridges but should include fastening devices for inhibiting relative movement between the abutment portions and pontic portions of a wax substructure which includes a plurality of abutment portions and a plurality of pontic portions.